Calculation of Ofloxacin Dose in Ear Drops
The 8-year-old patient will receive 0.75 mg of ofloxacin with each dose of 5 drops of the 3 mg/mL ear drops.
Calculation Method
To determine the exact dose of ofloxacin received with each administration, we need to perform the following calculation:
Given information:
- Ofloxacin concentration: 3 mg/mL
- Dose: 5 drops
- Dropper delivers: 20 drops per milliliter
Step-by-step calculation:
First, convert drops to milliliters:
- 5 drops ÷ 20 drops/mL = 0.25 mL
Then, calculate the amount of ofloxacin:
- 0.25 mL × 3 mg/mL = 0.75 mg
Verification with FDA Labeling
The calculated dose of 0.75 mg is consistent with the FDA-approved labeling for ofloxacin otic solution. According to the drug label 1, the recommended dosage for pediatric patients from 6 months to 13 years old with otitis externa is:
"Five drops (0.25 mL, 0.75 mg ofloxacin) instilled into the affected ear once daily for seven days."
This confirms our calculation is correct and aligns with the approved dosing for this age group.
Clinical Context
For external otitis in pediatric patients aged 6 months to 13 years, the FDA-approved regimen is 5 drops (0.75 mg ofloxacin) once daily for 7 days 1. This is exactly what was prescribed for this 8-year-old patient.
For older patients (13 years and older), the dose would be doubled to 10 drops (1.5 mg ofloxacin) once daily 1.
Important Administration Instructions
When counseling the mother, the pharmacist should also provide these important administration instructions:
- Warm the bottle by holding it in the hand for 1-2 minutes before administration to prevent dizziness
- Have the child lie with the affected ear upward during administration
- Maintain this position for 5 minutes after instilling the drops
- Keep the ear clean and dry during treatment
- Avoid swimming unless specifically permitted by the doctor
The correct dose of ofloxacin that the 8-year-old will receive with each dose is 0.75 mg.